On This Day . . .

…And Yet It Moves!

January 8, 1642: Galileo Dies

On this day in 1642, one of my hero’s, Galileo Galilei, dies in Italy at age 77. He has been referred to as the father of modern astronomy, the father of modern physics and the father of science. Damn, that’s a lot of fathering. [above: portrait of Galileo Galilei by Giusto Sustermans]

Statue of Galileo Galilei (1564-1642); outside of the Uffizi, Florence

Galileo, was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the scientific revolution. Considered the first person to use a telescope to observe the skies, he discovered the moons of Jupiter, the rings of Saturn, sun spots and yes, solar rotation, which brought him a lot of grief.

He confirmed Copernicus, that the Earth orbits the Sun. This didn’t sit well with the “powers” that be. He was charged with heresy by the Catholic Church and sentenced to life imprisonment . . . ouch!

Cristiano Banti’s 1857 painting Galileo facing the Roman Inquisition

In September 1632, Galileo was ordered to come to Rome to stand trial. In view of Galileo’s rather implausible denials, his final interrogation, in July 1633, concluded with his being threatened with torture if he did not tell the truth. The sentence of the Inquisition was delivered on June 22. It was in three essential parts:

Galileo was found “vehemently suspect of heresy”, namely of having held the opinions that:

The Sun lies motionless at the center of the universe,

that the Earth is not at its center and moves,

and that one may hold and defend an opinion as probable after it has been declared contrary to Holy Scripture.

He was sentenced to formal imprisonment at the pleasure of the Inquisition. On the following day this was commuted to house arrest, which he remained under for the rest of his life. His offending Dialogue was banned; and in an action not announced at the trial, publication of any of his works was forbidden, including any he might write in the future.

According to popular legend, after recanting his theory that the Earth moved around the Sun, Galileo allegedly muttered the rebellious phrase “And yet it moves”!

Galileo Portrait by Leoni

He displayed a peculiar ability to ignore established authorities, most notably Aristotelianism. In broader terms, his work marked another step towards the eventual separation of science from both philosophy and religion; a major development in human thought. He was often willing to change his views in accordance with observation

Galileo put forward the basic principle of relativity, that the laws of physics are the same in any system that is moving at a constant speed in a straight line, regardless of its particular speed or direction. Hence, there is no absolute motion or absolute rest. This principle provided the basic framework for Newton’s laws of motion and is central to Einstein’s special theory of relativity.

According to Stephen Hawking, Galileo probably bears more of the responsibility for the birth of modern science than anybody else, and Albert Einstein called him the father of modern science.

Galileo showing the Doge of Venice how to use the telescope (Fresco by Giuseppe Bertini)

One of the earliest surviving telescopes attributed to Galileo Galilei. In 1609, Galileo was, along with Englishman Thomas Harriot and others, among the first to use a refracting telescope as an instrument to observe stars, planets or moons.

The name “telescope” was coined for Galileo’s instrument by a Greek mathematician, Giovanni Demisiani, at a banquet held in 1611 by Prince Federico Cesi to make Galileo a member of his Accademia dei Lincei. The name was derived from the Greek tele = ‘far’ and skopein = ‘to look or see’. In 1610, he used a telescope at close range to magnify the parts of insects.

Galileo Microscope

Fellow academy member Giovanni Faber coined the word for Galileo’s invention from the Greek words μικρόν (micron) meaning “small”, and σκοπεῖν (skopein) meaning “to look at”. The word was meant to be analogous with “telescope”. Illustrations of insects made using one of Galileo’s microscopes, and published in 1625, appear to have been the first clear documentation of the use of a compound microscope.

It was on this page that Galileo first noted an observation of the moons of Jupiter. This observation upset the notion that all celestial bodies must revolve around the Earth. Galileo published a full description in Sidereus Nuncius in March 1610.The lower part of this sheet shows the use to which Galileo put this optical device: as he viewed the skies on successive evenings in January, 1610, he noted his first observations of the planet Jupiter and four of Jupiter’s moons.”